Many times discussed on the list and always the discussion is lengthy and
dispersed in opinions.
I personally recommend UNIX-systems thus if you are not interested in my
arguments please do not read the rest. And in your case p630 (four
generations after h50 in the same class) ought to be the best fit. With
newly anounced I/O drawer this one became a mighty beast.

As was already pointed the main argument ought to be the current skill
investment - usually change of the box and operating system means another
OS-admin working with the TSM admin. This incurs needs for some TSM
training of that OS admin and improvement of the TSM admin skills in the
new OS (if any).

Next important argument is necessary time for migration - move to a more
powerful same-platform box is just a matter of TSM DB restore (we do not
talk about version upgrade). Move to a different platform requires either
export/import (time consuming) or simultaneous work with both servers
until data expires (harder to maintain). For larger installations both
approaches can consume several months.

Except smallest installations prices for hardware are similar:
Althought (I)TSM is nearly equal on all platforms it relies on the box,
peripherals, operating system and drivers. Bean counters usually compare
processor clocks but this is least significant factor for a TSM server
performance. Size of TSM DB also is not a very good factor because it
shows mainly ammount of *all* data stored, not the daily change and
throughput requirements. Actually PCs can handle up to more than a
terabyte per night (3-4 LTO drives * 6-8 hours ~= 1.5 TB).
-       HP, IBM and Sun servers being mid-range systems are optimized for
large data crunching. They have more PCI buses therefore more I/O
througput. Number of buses for entry RISC systems is comparable to average
Intel-based box, average RISC systems can be compared only to high-end
8-16 processor Intels, while RISC systems with 8 or more processors do not
have equivalents in PC world.
-       TSM server is important component of the IT infrastructure and
very often cannot be stopped at all. (IMO) Windows requires much more
restarts than any UNIX and is less stable.
-       Intel-box peripherals involve more the processor in all I/O
operations.
-       RISC processors still perform more operations in a single clock
cycle. Intel processors focus on high clock-rate but small cache incurs
more time wasted idling until data comes from memory. RISC processors have
much larger caches and their memory bus width is 2-4 times more. My rule
of thumb is that 1 MHz of RISC processor clock is equal to about 1.5-2 MHz
of Intel (where 1.5x multiplier was for big cache Xeon processors)
-       in all kinds of Windows, TCP/IP stack is much more resource
consuming and with less total throughput.
-       list prices compared to actual deal prices - in the PC market
competition is very hard and margins are much lower; RISC systems have
much higher list prices but very often are sold with big discounts.
Usually bidget comparisons are made based on list prices which is somewhat
inaccurate.

As a result if we are talking about installations with little daily
changes (satisfiable by 2-3 HBAs and 1-2 LAN adapters) - nearly any box
can satisfy the requirements. So even entry (1-2 proc) Wintel box fits the
requirements and beats all others in price. Price range: <15k (EUR or
USD).
For average throughput requirements (four and more drives, usually several
100s GB diskpool, 3-4+ FC or many SCSI adapters) number of buses and slots
becomes main factor. Here compete RISC systems with 2-4 processors and
high-end 4-8 processor Intel-based systems. Price range: 30-100k
If number of drives in library(es) is more than 10 LTO/Magstar/9x40 or
15-16 DLT then even the mightiest Intels have to surrender and this is the
place for mid- to high-end RISCs and mainframes. Price range: 150k and
beyond. (I will be glad to be proven wrong by someone running with success
large number of drives over Windows)


Zlatko Krastev
IT Consultant







Ray Baughman <rbaughman AT NATIONALMACHINERY DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
11.11.2002 18:46
Please respond to "ADSM: Dist Stor Manager"


        To:     ADSM-L AT VM.MARIST DOT EDU
        cc:
        Subject:        Server AIX vs NT


Hello,

We are looking to replace our TSM server hardware, we are currently
running
the TSM server on an IBM H50.  The bean counters are saying that an NT
server would be a lot cheaper than a UNIX server.  They have decided it
needs to be either an IBM UNIX server or an NT server.  Has anyone had any
experience with both NT and AIX servers, and if so what information do you
have regarding performance, stability etc. with one over the other.
Basically I've be told to either cost justify AIX or I'll end up on NT.

Any help would be appreciated.

Ray Baughman
Engineering Systems Administrator
TSM Administrator
National Machinery LLC
Phone 419-443-2257
Fax 419-443-2376
Email rbaughman AT nationalmachinery DOT com